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Finding the Fourth Proportional to 138.41, 206.48 and 128.58

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Solution

The fourth proportional to 138.41, 206.48 and 128.58 is: 191.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.41 : 206.48 = 128.58 : x
  2. Step 2: Convert to fraction form
    138.41/206.48 = 128.58/x
  3. Step 3: Cross multiply
    138.41x = 206.48 × 128.58
  4. Step 4: Simplify right side
    138.41x = 26,548.56
  5. Step 5: Solve for x
    x = 26,548.56/138.41
  6. Step 6: Final answer
    x = 191.82

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.